The BBC's Adam Mynott says the turnout was much larger than expected, and described it as an expression of solidarity with the interim government.

The minister had hoped to make Afghanistan a tourist destination

Seven people have been arrested in connection with the killing, at Kabul airport on Thursday, and Saudi Arabia has said it will return another three suspects to Afghanistan.

Questions are being asked in Kabul as to how the minister could have been held for several hours at the airport and beaten to death without the intervention of Afghan security forces or the UK-led international peacekeeping force.

All 10 suspects - who include three senior government officials - appear to be members of an Afghan Northern Alliance faction led by Ahmed Shah Masood, who was assassinated last year.

Mr Karzai said Rahman had had a long-running personal feud with the officials, who had worked in the intelligence, defence and justice ministries.

Our correspondent says the administration is rallying round to give at least an outward impression of solidarity.

Mr Karzai accompanied the coffin

The coffin was covered with the black, green and red Afghan flag and strewn with flowers.

It was taken to the city mosque, where a sea of mourners in camouflage fatigues and traditional costume raised their hands in prayer.

And about 1,000 people gathered at the cemetery for the burial and more prayers.

Helicopters flew over the city and troops lined the streets.

The troops were mainly Afghan, and international peacekeepers kept a low profile.

Senior figures

The attack was initially blamed on pilgrims on their way to Mecca who were angered by long delays to their flights.

However those who have since been detained were reported to include General Abdullah Jan Tawhidi, in charge of Afghanistan's intelligence service department, and General Kalandar Beg, a deputy in the defence ministry.

The three most senior suspects all come from the Panjshir Valley and from the armed faction Jamiat-e-Islami, part of the victorious Northern Alliance which entered Kabul after the Taleban fled.

Split

Suspects include:

General Abdullah Jan Tawhidi - head of intelligence services' political office

General Kalandar Beg - deputy defence minister for technical affairs

Saranwal Alim - justice ministry official

Most people working in the security services are commanders or fighters from this faction.

Rahman once belonged to this group before breaking away to ally himself with the former king of Afghanistan.

The 10 suspects appear to have believed that they could act with impunity, as no member of the Afghan security forces intervened.

International peacekeepers based at the airport said they had received no request for assistance during the attack on the minister.

"The matter of the minister of aviation we were not aware of. We were not in view of the area of the reported incident, and at no stage were we asked to intervene," said a senior British officer.

Lieutenant Colonel Neal Peckham said he believed there was no immediate connection between Rahman's killing and an incident early on Saturday in which UK peacekeeping troops were shot at for the first time in Afghanistan.

Troops returned fire after an unidentified gunman attacked an observation post, and an investigation is now under way.